Rod-shaped lamp and heat treatment apparatus

ABSTRACT

Halogen lamps arranged in two, upper and lower, tiers to intersect each other in a lattice pattern are provided under a chamber for receiving a semiconductor wafer therein. In a location where the halogen lamps in the upper and lower tiers overlap each other, a reflector is provided such that an outer wall surface of a glass tube of each halogen lamp is open on upper and lower sides. In the location where the halogen lamps in the upper and lower tiers overlap each other, light emitted upwardly from a halogen lamp in the lower tier is transmitted through the open upper and lower portions of the outer wall surface of the glass tube of a halogen lamp in the upper tier, and is directed further upwardly. Thus, the light is prevented from entering the glass tube of the halogen lamp in the lower tier again.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a rod-shaped lamp which irradiates athin plate-like precision electronic substrate (hereinafter referred tosimply as a “substrate”) such as a semiconductor wafer with light toheat the substrate, and a heat treatment apparatus including therod-shaped lamp.

Description of the Background Art

In the process of manufacturing a semiconductor device, impurity dopingis an essential step for forming a pn junction in a semiconductor wafer.At present, it is common practice to perform impurity doping by an ionimplantation process and a subsequent annealing process. The ionimplantation process is a technique for causing ions of impurityelements such as boron (B), arsenic (As) and phosphorus (P) to collideagainst the semiconductor wafer with high acceleration voltage, therebyphysically implanting the impurities into the semiconductor wafer. Theimplanted impurities are activated by the subsequent annealing process.When annealing time in this annealing process is approximately severalseconds or longer, the implanted impurities are deeply diffused by heat.This results in a junction depth much greater than a required depth,which might constitute a hindrance to good device formation.

In recent years, attention has been given to flash lamp annealing (FLA)that is an annealing technique for heating a semiconductor wafer in anextremely short time. The flash lamp annealing is a heat treatmenttechnique in which xenon flash lamps (the term “flash lamp” as usedhereinafter refers to a “xenon flash lamp”) are used to irradiate asurface of a semiconductor wafer with a flash of light, thereby raisingthe temperature of only the surface of the semiconductor wafer implantedwith impurities in an extremely short time (several milliseconds orless).

The xenon flash lamps have a spectral distribution of radiation rangingfrom ultraviolet to near-infrared regions. The wavelength of lightemitted from the xenon flash lamps is shorter than that of light emittedfrom conventional halogen lamps, and approximately coincides with afundamental absorption band of a silicon semiconductor wafer. Thus, whena semiconductor wafer is irradiated with a flash of light emitted fromthe xenon flash lamps, the temperature of the semiconductor wafer can beraised rapidly, with only a small amount of light transmitted throughthe semiconductor wafer. Also, it has turned out that flash irradiation,that is, the irradiation of a semiconductor wafer with a flash of lightin an extremely short time of several milliseconds or less allows aselective temperature rise only near the surface of the semiconductorwafer. Therefore, the temperature rise in an extremely short time withthe xenon flash lamps allows only the activation of impurities to beachieved without deep diffusion of the impurities.

A heat treatment apparatus employing such xenon flash lamps is disclosedin Japanese Patent Application Laid-Open No. 2016-181656 in which theflash lamps are disposed on the front surface side of a semiconductorwafer whereas halogen lamps are disposed on the back surface sidethereof, so that a desired heat treatment is performed by thecombination of the flash lamps and the halogen lamps. In the heattreatment apparatus disclosed in Japanese Patent Application Laid-OpenNo. 2016-181656, the semiconductor wafer is preheated to a certaindegree of temperature by the halogen lamps, and the temperature of thesemiconductor wafer is thereafter increased to a desired treatmenttemperature by pulse heating from the flash lamps. Also in the heattreatment apparatus disclosed in Japanese Patent Application Laid-OpenNo. 2016-181656, the halogen lamps are arranged to intersect each otherin a lattice pattern, and a reflector is provided on a tube wall of eachof the halogen lamps for the purpose of increasing the directivity ofexiting light.

Unfortunately, there have been cases in which the provision of thereflector directly on an outer wall surface of a halogen lamp gives riseto a problem such that a glass tube of the halogen lamp is broken. Inparticular, when halogen lamps are arranged in two tiers, i.e. upper andlower tiers, to intersect each other in a lattice pattern as disclosedin Japanese Patent Application Laid-Open No. 2016-181656, a phenomenonin which glass tubes are broken due to melting at points of intersectionof the upper and lower halogen lamps has occurred.

SUMMARY OF THE INVENTION

The present invention is intended for a rod-shaped lamp for heating asubstrate.

According to one aspect of the present invention, the rod-shaped lampcomprises: a cylindrical glass tube; and a reflector provided on anouter wall surface of the glass tube, the reflector being provided suchthat the outer wall surface is open on one side of the glass tube asseen in a radial direction thereof and on the other side thereofopposite the one side.

Light emitted in the glass tube exits the outer wall surface on the oneside and on the other side. This prevents the breakage of the glasstube.

The present invention is also intended for a heat treatment apparatusfor heating a substrate by irradiating the substrate with light.

According to another aspect of the present invention, the heat treatmentapparatus comprises: a chamber for receiving a substrate therein; aholder for holding the substrate in the chamber; and a plurality ofrod-shaped lamps provided over or under the chamber and for irradiatingthe substrate held by the holder with light, the rod-shaped lamps beingarranged in two, upper and lower, tiers in a lattice pattern, each ofthe rod-shaped lamps including a cylindrical glass tube, and a reflectorprovided on an outer wall surface of the glass tube, the reflector beingprovided such that the outer wall surface is open on upper and lowersides of the glass tube in a location where the rod-shaped lamps in theupper and lower tiers overlap each other.

Light emitted in the glass tube exits the outer wall surface on theupper and lower sides. This prevents the breakage of the glass tube.

It is therefore an object of the present invention to prevent thebreakage of a glass tube of a rod-shaped lamp.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view showing a configuration of aheat treatment apparatus according to the present invention;

FIG. 2 is a perspective view showing the entire external appearance of aholder;

FIG. 3 is a plan view of a susceptor;

FIG. 4 is a sectional view of the susceptor;

FIG. 5 is a plan view of a transfer mechanism;

FIG. 6 is a side view of the transfer mechanism;

FIG. 7 is a plan view showing an arrangement of halogen lamps;

FIG. 8 is a view showing a reflector provided on a halogen lamp in alocation where the halogen lamps in upper and lower tiers overlap eachother;

FIG. 9 is a view showing the reflector provided on a halogen lamp in alocation where the halogen lamps in the upper and lower tiers do notoverlap each other;

FIG. 10 is a view showing a phenomenon occurring in a location where thehalogen lamps in the upper and lower tiers overlap each other when thereflector is provided over a wide area; and

FIG. 11 is a view showing a phenomenon occurring in a location where thehalogen lamps in the upper and lower tiers overlap each other when thereflector is provided such that upper and lower portions thereof areopen.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment according to the present invention will now bedescribed in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a configuration of aheat treatment apparatus 1 according to the present invention. The heattreatment apparatus 1 of FIG. 1 is a flash lamp annealer for irradiatinga disk-shaped semiconductor wafer W serving as a substrate with flashesof light to heat the semiconductor wafer W. The size of thesemiconductor wafer W to be treated is not particularly limited. Forexample, the semiconductor wafer W to be treated has a diameter of 300mm and 450 mm (in the present preferred embodiment, 300 mm). Thesemiconductor wafer W prior to the transport into the heat treatmentapparatus 1 is implanted with impurities. The heat treatment apparatus 1performs a heating treatment on the semiconductor wafer W to therebyactivate the impurities implanted in the semiconductor wafer W. Itshould be noted that the dimensions of components and the number ofcomponents are shown in exaggeration or in simplified form, asappropriate, in FIG. 1 and the subsequent figures for the sake of easierunderstanding.

The heat treatment apparatus 1 includes a chamber 6 for receiving asemiconductor wafer W therein, a flash heating part 5 including aplurality of built-in flash lamps FL, and a halogen heating part 4including a plurality of built-in halogen lamps HL. The flash heatingpart 5 is provided over the chamber 6, and the halogen heating part 4 isprovided under the chamber 6. The heat treatment apparatus 1 furtherincludes a holder 7 provided inside the chamber 6 and for holding asemiconductor wafer W in a horizontal attitude, and a transfer mechanism10 provided inside the chamber 6 and for transferring a semiconductorwafer W between the holder 7 and the outside of the heat treatmentapparatus 1. The heat treatment apparatus 1 further includes acontroller 3 for controlling operating mechanisms provided in thehalogen heating part 4, the flash heating part 5, and the chamber 6 tocause the operating mechanisms to heat-treat a semiconductor wafer W.

The chamber 6 is configured such that upper and lower chamber windows 63and 64 made of quartz are mounted to the top and bottom, respectively,of a tubular chamber side portion 61. The chamber side portion 61 has agenerally tubular shape having an open top and an open bottom. The upperchamber window 63 is mounted to block the top opening of the chamberside portion 61, and the lower chamber window 64 is mounted to block thebottom opening thereof. The upper chamber window 63 forming the ceilingof the chamber 6 is a disk-shaped member made of quartz, and serves as aquartz window that transmits flashes of light emitted from the flashheating part 5 therethrough into the chamber 6. The lower chamber window64 forming the floor of the chamber 6 is also a disk-shaped member madeof quartz, and serves as a quartz window that transmits light emittedfrom the halogen heating part 4 therethrough into the chamber 6.

An upper reflective ring 68 is mounted to an upper portion of the innerwall surface of the chamber side portion 61, and a lower reflective ring69 is mounted to a lower portion thereof. Both of the upper and lowerreflective rings 68 and 69 are in the form of an annular ring. The upperreflective ring 68 is mounted by being inserted downwardly from the topof the chamber side portion 61. The lower reflective ring 69, on theother hand, is mounted by being inserted upwardly from the bottom of thechamber side portion 61 and fastened with screws not shown. In otherwords, the upper and lower reflective rings 68 and 69 are removablymounted to the chamber side portion 61. An interior space of the chamber6, i.e. a space surrounded by the upper chamber window 63, the lowerchamber window 64, the chamber side portion 61, and the upper and lowerreflective rings 68 and 69, is defined as a heat treatment space 65.

A recessed portion 62 is defined in the inner wall surface of thechamber 6 by mounting the upper and lower reflective rings 68 and 69 tothe chamber side portion 61. Specifically, the recessed portion 62 isdefined which is surrounded by a middle portion of the inner wallsurface of the chamber side portion 61 where the reflective rings 68 and69 are not mounted, a lower end surface of the upper reflective ring 68,and an upper end surface of the lower reflective ring 69. The recessedportion 62 is provided in the form of a horizontal annular ring in theinner wall surface of the chamber 6, and surrounds the holder 7 whichholds a semiconductor wafer W. The chamber side portion 61 and the upperand lower reflective rings 68 and 69 are made of a metal material (e.g.,stainless steel) with high strength and high heat resistance.

The chamber side portion 61 is provided with a transport opening(throat) 66 for the transport of a semiconductor wafer W therethroughinto and out of the chamber 6. The transport opening 66 is openable andclosable by a gate valve 185. The transport opening 66 is connected incommunication with an outer peripheral surface of the recessed portion62. Thus, when the transport opening 66 is opened by the gate valve 185,a semiconductor wafer W is allowed to be transported through thetransport opening 66 and the recessed portion 62 into and out of theheat treatment space 65. When the transport opening 66 is closed by thegate valve 185, the heat treatment space 65 in the chamber 6 is anenclosed space.

The chamber side portion 61 is further provided with a through hole 61 abored therein. A radiation thermometer 20 is mounted to a location of anouter wall surface of the chamber side portion 61 where the through hole61 a is provided. The through hole 61 a is a cylindrical hole fordirecting infrared radiation emitted from the lower surface of asemiconductor wafer W held by a susceptor 74 to be described latertherethrough to the radiation thermometer 20. The through hole 61 a isinclined with respect to a horizontal direction so that a longitudinalaxis (an axis extending in a direction in which the through hole 61 aextends through the chamber side portion 61) of the through hole 61 aintersects a main surface of the semiconductor wafer W held by thesusceptor 74. A transparent window 21 made of barium fluoride materialtransparent to infrared radiation in a wavelength range measurable withthe radiation thermometer 20 is mounted to an end portion of the throughhole 61 a which faces the heat treatment space 65.

At least one gas supply opening 81 for supplying a treatment gastherethrough into the heat treatment space 65 is provided in an upperportion of the inner wall of the chamber 6. The gas supply opening 81 isprovided above the recessed portion 62, and may be provided in the upperreflective ring 68. The gas supply opening 81 is connected incommunication with a gas supply pipe 83 through a buffer space 82provided in the form of an annular ring inside the side wall of thechamber 6. The gas supply pipe 83 is connected to a treatment gas supplysource 85. A valve 84 is inserted at some midpoint in the gas supplypipe 83. When the valve 84 is opened, the treatment gas is fed from thetreatment gas supply source 85 to the buffer space 82. The treatment gasflowing in the buffer space 82 flows in a spreading manner within thebuffer space 82 which is lower in fluid resistance than the gas supplyopening 81, and is supplied through the gas supply opening 81 into theheat treatment space 65. Examples of the treatment gas usable hereininclude inert gases such as nitrogen gas (N₂), reactive gases such ashydrogen (H₂) and ammonia (NH₃), and mixtures of these gases (althoughnitrogen gas is used in this preferred embodiment).

At least one gas exhaust opening 86 for exhausting a gas from the heattreatment space 65 is provided in a lower portion of the inner wall ofthe chamber 6. The gas exhaust opening 86 is provided below the recessedportion 62, and may be provided in the lower reflective ring 69. The gasexhaust opening 86 is connected in communication with a gas exhaust pipe88 through a buffer space 87 provided in the form of an annular ringinside the side wall of the chamber 6. The gas exhaust pipe 88 isconnected to an exhaust part 190. A valve 89 is inserted at somemidpoint in the gas exhaust pipe 88. When the valve 89 is opened, thegas in the heat treatment space 65 is exhausted through the gas exhaustopening 86 and the buffer space 87 to the gas exhaust pipe 88. The atleast one gas supply opening 81 and the at least one gas exhaust opening86 may include a plurality of gas supply openings 81 and a plurality ofgas exhaust openings 86, respectively, arranged in a circumferentialdirection of the chamber 6, and may be in the form of slits. Thetreatment gas supply source 85 and the exhaust part 190 may bemechanisms provided in the heat treatment apparatus 1 or be utilitysystems in a factory in which the heat treatment apparatus 1 isinstalled.

A gas exhaust pipe 191 for exhausting the gas from the heat treatmentspace 65 is also connected to a distal end of the transport opening 66.The gas exhaust pipe 191 is connected through a valve 192 to the exhaustpart 190. By opening the valve 192, the gas in the chamber 6 isexhausted through the transport opening 66.

FIG. 2 is a perspective view showing the entire external appearance ofthe holder 7. The holder 7 includes a base ring 71, coupling portions72, and the susceptor 74. The base ring 71, the coupling portions 72,and the susceptor 74 are all made of quartz. In other words, the wholeof the holder 7 is made of quartz.

The base ring 71 is a quartz member having an arcuate shape obtained byremoving a portion from an annular shape. This removed portion isprovided to prevent interference between transfer arms 11 of thetransfer mechanism 10 to be described later and the base ring 71. Thebase ring 71 is supported by a wall surface of the chamber 6 by beingplaced on the bottom surface of the recessed portion 62 (with referenceto FIG. 1). The multiple coupling portions 72 (in the present preferredembodiment, four coupling portions 72) are mounted upright on the uppersurface of the base ring 71 and arranged in a circumferential directionof the annular shape thereof. The coupling portions 72 are quartzmembers, and are rigidly secured to the base ring 71 by welding.

The susceptor 74 is supported by the four coupling portions 72 providedon the base ring 71. FIG. 3 is a plan view of the susceptor 74. FIG. 4is a sectional view of the susceptor 74. The susceptor 74 includes aholding plate 75, a guide ring 76, and a plurality of substrate supportpins 77. The holding plate 75 is a generally circular planar member madeof quartz. The diameter of the holding plate 75 is greater than that ofa semiconductor wafer W. In other words, the holding plate 75 has asize, as seen in plan view, greater than that of the semiconductor waferW.

The guide ring 76 is provided on a peripheral portion of the uppersurface of the holding plate 75. The guide ring 76 is an annular memberhaving an inner diameter greater than the diameter of the semiconductorwafer W. For example, when the diameter of the semiconductor wafer W is300 mm, the inner diameter of the guide ring 76 is 320 mm. The innerperiphery of the guide ring 76 is in the form of a tapered surface whichbecomes wider in an upward direction from the holding plate 75. Theguide ring 76 is made of quartz similar to that of the holding plate 75.The guide ring 76 may be welded to the upper surface of the holdingplate 75 or fixed to the holding plate 75 with separately machined pinsand the like. Alternatively, the holding plate 75 and the guide ring 76may be machined as an integral member.

A region of the upper surface of the holding plate 75 which is insidethe guide ring 76 serves as a planar holding surface 75 a for holdingthe semiconductor wafer W. The substrate support pins 77 are providedupright on the holding surface 75 a of the holding plate 75. In thepresent preferred embodiment, a total of 12 substrate support pins 77provided upright are spaced at intervals of 30 degrees along thecircumference of a circle concentric with the outer circumference of theholding surface 75 a (the inner circumference of the guide ring 76). Thediameter of the circle on which the 12 substrate support pins 77 aredisposed (the distance between opposed ones of the substrate supportpins 77) is slightly smaller than the diameter of the semiconductorwafer W, and is 270 to 280 mm (in the present preferred embodiment, 270mm) when the diameter of the semiconductor wafer W is 300 mm. Each ofthe substrate support pins 77 is made of quartz. The substrate supportpins 77 may be provided by welding on the upper surface of the holdingplate 75 or machined integrally with the holding plate 75.

Referring again to FIG. 2, the four coupling portions 72 providedupright on the base ring 71 and the peripheral portion of the holdingplate 75 of the susceptor 74 are rigidly secured to each other bywelding. In other words, the susceptor 74 and the base ring 71 arefixedly coupled to each other with the coupling portions 72. The basering 71 of such a holder 7 is supported by the wall surface of thechamber 6, whereby the holder 7 is mounted to the chamber 6. With theholder 7 mounted to the chamber 6, the holding plate 75 of the susceptor74 assumes a horizontal attitude (an attitude such that the normal tothe susceptor 74 coincides with a vertical direction). In other words,the holding surface 75 a of the holding plate 75 becomes a horizontalsurface.

A semiconductor wafer W transported into the chamber 6 is placed andheld in a horizontal attitude on the susceptor 74 of the holder 7mounted to the chamber 6. At this time, the semiconductor wafer W issupported by the 12 substrate support pins 77 provided upright on theholding plate 75, and is held by the susceptor 74. More strictlyspeaking, the 12 substrate support pins 77 have respective upper endportions coming in contact with the lower surface of the semiconductorwafer W to support the semiconductor wafer W. The semiconductor wafer Wis supported in a horizontal attitude by the 12 substrate support pins77 because the 12 substrate support pins 77 have a uniform height(distance from the upper ends of the substrate support pins 77 to theholding surface 75 a of the holding plate 75).

The semiconductor wafer W supported by the substrate support pins 77 isspaced a predetermined distance apart from the holding surface 75 a ofthe holding plate 75. The thickness of the guide ring 76 is greater thanthe height of the substrate support pins 77. Thus, the guide ring 76prevents the horizontal misregistration of the semiconductor wafer Wsupported by the substrate support pins 77.

As shown in FIGS. 2 and 3, an opening 78 is formed in the holding plate75 of the susceptor 74 so as to extend vertically through the holdingplate 75 of the susceptor 74. The opening 78 is provided for theradiation thermometer 20 to receive radiation (infrared radiation)emitted from the lower surface of the semiconductor wafer W.Specifically, the radiation thermometer 20 receives the radiationemitted from the lower surface of the semiconductor wafer W through theopening 78 and the transparent window 21 mounted to the through hole 61a in the chamber side portion 61 to measure the temperature of thesemiconductor wafer W. Further, the holding plate 75 of the susceptor 74further includes four through holes 79 bored therein and designed sothat lift pins 12 of the transfer mechanism 10 to be described laterpass through the through holes 79, respectively, to transfer asemiconductor wafer W.

FIG. 5 is a plan view of the transfer mechanism 10. FIG. 6 is a sideview of the transfer mechanism 10. The transfer mechanism 10 includesthe two transfer arms 11. The transfer arms 11 are of an arcuateconfiguration extending substantially along the annular recessed portion62. Each of the transfer arms 11 includes the two lift pins 12 mountedupright thereon. The transfer arms 11 and the lift pins 12 are made ofquartz. The transfer arms 11 are pivotable by a horizontal movementmechanism 13. The horizontal movement mechanism 13 moves the pair oftransfer arms 11 horizontally between a transfer operation position (aposition indicated by solid lines in FIG. 5) in which a semiconductorwafer W is transferred to and from the holder 7 and a retracted position(a position indicated by dash-double-dot lines in FIG. 5) in which thetransfer arms 11 do not overlap the semiconductor wafer W held by theholder 7 as seen in plan view. The horizontal movement mechanism 13 maybe of the type which causes individual motors to pivot the transfer arms11 respectively or of the type which uses a linkage mechanism to cause asingle motor to pivot the pair of transfer arms 11 in cooperativerelation.

The transfer arms 11 are moved upwardly and downwardly together with thehorizontal movement mechanism 13 by an elevating mechanism 14. As theelevating mechanism 14 moves up the pair of transfer arms 11 in theirtransfer operation position, the four lift pins 12 in total pass throughthe respective four through holes 79 (with reference to FIGS. 2 and 3)bored in the susceptor 74, so that the upper ends of the lift pins 12protrude from the upper surface of the susceptor 74. On the other hand,as the elevating mechanism 14 moves down the pair of transfer arms 11 intheir transfer operation position to take the lift pins 12 out of therespective through holes 79 and the horizontal movement mechanism 13moves the pair of transfer arms 11 so as to open the transfer arms 11,the transfer arms 11 move to their retracted position. The retractedposition of the pair of transfer arms 11 is immediately over the basering 71 of the holder 7. The retracted position of the transfer arms 11is inside the recessed portion 62 because the base ring 71 is placed onthe bottom surface of the recessed portion 62. An exhaust mechanism notshown is also provided near the location where the drivers (thehorizontal movement mechanism 13 and the elevating mechanism 14) of thetransfer mechanism 10 are provided, and is configured to exhaust anatmosphere around the drivers of the transfer mechanism 10 to theoutside of the chamber 6.

Referring again to FIG. 1, the flash heating part 5 provided over thechamber 6 includes an enclosure 51, a light source provided inside theenclosure 51 and including the multiple (in the present preferredembodiment, 30) xenon flash lamps FL, and a reflector 52 provided insidethe enclosure 51 so as to cover the light source from above. The flashheating part 5 further includes a lamp light radiation window 53 mountedto the bottom of the enclosure 51. The lamp light radiation window 53forming the floor of the flash heating part 5 is a plate-like quartzwindow made of quartz. The flash heating part 5 is provided over thechamber 6, whereby the lamp light radiation window 53 is opposed to theupper chamber window 63. The flash lamps FL direct flashes of light fromover the chamber 6 through the lamp light radiation window 53 and theupper chamber window 63 toward the heat treatment space 65.

The flash lamps FL, each of which is a rod-shaped lamp having anelongated cylindrical shape, are arranged in a plane so that thelongitudinal directions of the respective flash lamps FL are in parallelwith each other along a main surface of a semiconductor wafer W held bythe holder 7 (that is, in a horizontal direction). Thus, a plane definedby the arrangement of the flash lamps FL is also a horizontal plane. Aregion in which the flash lamps FL are arranged has a size, as seen inplan view, greater than that of the semiconductor wafer W.

Each of the xenon flash lamps FL includes a cylindrical glass tube(discharge tube) containing xenon gas sealed therein and having positiveand negative electrodes provided on opposite ends thereof and connectedto a capacitor, and a trigger electrode attached to the outer peripheralsurface of the glass tube. Because the xenon gas is electricallyinsulative, no current flows in the glass tube in a normal state even ifelectrical charge is stored in the capacitor. However, if a high voltageis applied to the trigger electrode to produce an electrical breakdown,electricity stored in the capacitor flows momentarily in the glass tube,and xenon atoms or molecules are excited at this time to cause lightemission. Such a xenon flash lamp FL has the property of being capableof emitting extremely intense light as compared with a light source thatstays lit continuously such as a halogen lamp HL because theelectrostatic energy previously stored in the capacitor is convertedinto an ultrashort light pulse ranging from 0.1 to 100 milliseconds.Thus, the flash lamps FL are pulsed light emitting lamps which emitlight instantaneously for an extremely short time period of less thanone second. The light emission time of the flash lamps FL is adjustableby the coil constant of a lamp light source which supplies power to theflash lamps FL.

The reflector 52 is provided over the plurality of flash lamps FL so asto cover all of the flash lamps FL. A fundamental function of thereflector 52 is to reflect flashes of light emitted from the pluralityof flash lamps FL toward the heat treatment space 65. The reflector 52is a plate made of an aluminum alloy. A surface of the reflector 52 (asurface which faces the flash lamps FL) is roughened by abrasiveblasting.

The halogen heating part 4 provided under the chamber 6 includes anenclosure 41 incorporating the multiple (in the present preferredembodiment, 40) halogen lamps HL. The halogen heating part 4 is a lightirradiator that directs light from under the chamber 6 through the lowerchamber window 64 toward the heat treatment space 65 to heat thesemiconductor wafer W by means of the halogen lamps HL.

FIG. 7 is a plan view showing an arrangement of the multiple halogenlamps HL. The 40 halogen lamps HL are arranged in two tiers, i.e. upperand lower tiers. That is, 20 halogen lamps HL are arranged in the uppertier closer to the holder 7, and 20 halogen lamps HL are arranged in thelower tier farther from the holder 7 than the upper tier. Each of thehalogen lamps HL is a rod-shaped lamp having an elongated cylindricalshape. The 20 halogen lamps HL in each of the upper and lower tiers arearranged so that the longitudinal directions thereof are in parallelwith each other along a main surface of a semiconductor wafer W held bythe holder 7 (that is, in a horizontal direction). Thus, a plane definedby the arrangement of the halogen lamps HL in each of the upper andlower tiers is also a horizontal plane.

As shown in FIG. 7, the halogen lamps HL in each of the upper and lowertiers are disposed at a higher density in a region opposed to aperipheral portion of the semiconductor wafer W held by the holder 7than in a region opposed to a central portion thereof. In other words,the halogen lamps HL in each of the upper and lower tiers are arrangedat shorter intervals in the peripheral portion of the lamp arrangementthan in the central portion thereof. This allows a greater amount oflight to impinge upon the peripheral portion of the semiconductor waferW where a temperature decrease is prone to occur when the semiconductorwafer W is heated by the irradiation thereof with light from the halogenheating part 4.

The group of halogen lamps HL in the upper tier and the group of halogenlamps HL in the lower tier are arranged to intersect each other in alattice pattern. In other words, the 40 halogen lamps HL in total aredisposed so that the longitudinal direction of the 20 halogen lamps HLarranged in the upper tier and the longitudinal direction of the 20halogen lamps HL arranged in the lower tier are orthogonal to eachother.

Each of the halogen lamps HL is a filament-type light source whichpasses current through a filament disposed in a cylindrical glass tubeto make the filament incandescent, thereby emitting light. A gasprepared by introducing a halogen element (iodine, bromine and the like)in trace amounts into an inert gas such as nitrogen, argon and the likeis sealed in the glass tube. The introduction of the halogen elementallows the temperature of the filament to be set at a high temperaturewhile suppressing a break in the filament. Thus, the halogen lamps HLhave the properties of having a longer life than typical incandescentlamps and being capable of continuously emitting intense light. Thus,the halogen lamps HL are continuous lighting lamps that emit lightcontinuously for at least not less than one second. In addition, thehalogen lamps HL, which are rod-shaped lamps, have a long life. Thearrangement of the halogen lamps HL in a horizontal direction providesgood efficiency of radiation toward the semiconductor wafer W providedover the halogen lamps HL.

A reflector 43 is provided also inside the enclosure 41 of the halogenheating part 4 and under the halogen lamps HL arranged in two tiers(FIG. 1). The reflector 43 reflects the light emitted from the halogenlamps HL toward the heat treatment space 65.

In addition to the reflector 43 for the entire halogen heating part 4,individual reflectors are provided for the respective halogen lamps HL.FIGS. 8 and 9 are sectional views of the rod-shaped halogen lamps HLtaken in a direction perpendicular to the longitudinal directionthereof. FIGS. 8 and 9 differ from each other in position in which thehalogen lamps HL are taken. Each of the halogen lamps HL includes acylindrical glass tube 48, and a filament 49 disposed in a centralportion of the glass tube 48. A reflector 47 for increasing thedirectivity of exiting light is provided on an outer wall surface of theglass tube 48. The reflector 47 is formed by applying a ceramics-basedsolvent to the outer wall surface of the glass tube 48 of each of thehalogen lamps HL and then drying the applied film. The configurations ofthe reflectors 47 provided for the halogen lamps HL differ betweenlocations where the halogen lamps HL in the upper and lower tiersoverlap each other in the arrangement of the 40 halogen lamps HL andother locations.

FIG. 8 is a view showing the reflector 47 provided on a halogen lamp HLin a location where the halogen lamps HL in the upper and lower tiersoverlap each other. The location where the halogen lamps HL in the upperand lower tiers overlap each other refers to a location where a halogenlamp HL in the upper tier and a halogen lamp HL in the lower tierintersect each other, for example, as indicated by the referencecharacter A in FIG. 7. In the present preferred embodiment, there aremultiple locations where the halogen lamps HL in the upper and lowertiers overlap each other as indicated by the reference character A inFIG. 7 because the halogen lamps HL are arranged in two tiers, i.e.upper and lower tiers, to intersect each other in a lattice pattern. Insuch a location where the halogen lamps HL in the upper and lower tiersoverlap each other, the reflector 47 is provided such that the outerwall surface of the glass tube 48 of a halogen lamp HL in each of theupper and lower tiers is open on upper and lower sides, as shown in FIG.8. Specifically, the reflector 47 is provided to cover an area extendingfor 90 degrees of the outer wall surface on each of the opposite lateralsides of the glass tube 48 as seen from the center of the glass tube 48(the position of the filament 49). As a result, an area extending for 90degrees of the outer wall surface on each of the upper and lower sidesof the glass tube 48 as seen from the center of the glass tube 48 isopen.

FIG. 9 is a view showing the reflector 47 provided on a halogen lamp HLin a location where the halogen lamps HL in the upper and lower tiers donot overlap each other. Such locations where the halogen lamps HL in theupper and lower tiers do not overlap each other refer to regions of thehalogen lamps HL other than the locations where the halogen lamps HL inthe upper and lower tiers overlap each other as indicated by thereference character A in FIG. 7. In such a location where the halogenlamps HL in the upper and lower tiers do not overlap each other, thereflector 47 is provided such that the outer wall surface of the glasstube 48 of a halogen lamp HL is open only on the upper side, as shown inFIG. 9. Specifically, the reflector 47 is provided to cover an areaextending for 270 degrees of the outer wall surface from the left-handside of the glass tube 48 through the lower side thereof to theright-hand side thereof as seen from the center of the glass tube 48. Asa result, an area extending for 90 degrees of the outer wall surface onthe upper side of the glass tube 48 as seen from the center of the glasstube 48 is open.

The controller 3 controls the aforementioned various operatingmechanisms provided in the heat treatment apparatus 1. The controller 3is similar in hardware configuration to a typical computer.Specifically, the controller 3 includes a CPU that is a circuit forperforming various computation processes, a ROM or read-only memory forstoring a basic program therein, a RAM or readable/writable memory forstoring various pieces of information therein, and a magnetic disk forstoring control software, data and the like therein. The CPU in thecontroller 3 executes a predetermined processing program, whereby theprocesses in the heat treatment apparatus 1 proceed.

The heat treatment apparatus 1 further includes, in addition to theaforementioned components, various cooling structures to prevent anexcessive temperature rise in the halogen heating part 4, the flashheating part 5 and the chamber 6 because of the heat energy generatedfrom the halogen lamps HL and the flash lamps FL during the heattreatment of a semiconductor wafer W. As an example, a water coolingtube (not shown) is provided in the walls of the chamber 6. Also, thehalogen heating part 4 and the flash heating part 5 have an air coolingstructure for forming a gas flow therein to exhaust heat. Air issupplied to a gap between the upper chamber window 63 and the lamp lightradiation window 53 to cool down the flash heating part 5 and the upperchamber window 63.

Next, a procedure for the treatment of a semiconductor wafer W in theheat treatment apparatus 1 will be described. A semiconductor wafer W tobe treated herein is a semiconductor substrate doped with impurities(ions) by an ion implantation process. The impurities are activated bythe heat treatment apparatus 1 performing the process of heating(annealing) the semiconductor wafer W by irradiation with a flash oflight. The procedure for the treatment in the heat treatment apparatus 1which will be described below proceeds under the control of thecontroller 3 over the operating mechanisms of the heat treatmentapparatus 1.

First, the valve 84 for supply of gas is opened, and the valves 89 and192 for exhaust of gas are opened, so that the supply and exhaust of gasinto and out of the chamber 6 start. When the valve 84 is opened,nitrogen gas is supplied through the gas supply opening 81 into the heattreatment space 65. When the valve 89 is opened, the gas within thechamber 6 is exhausted through the gas exhaust opening 86. This causesthe nitrogen gas supplied from an upper portion of the heat treatmentspace 65 in the chamber 6 to flow downwardly and then to be exhaustedfrom a lower portion of the heat treatment space 65.

The gas within the chamber 6 is exhausted also through the transportopening 66 by opening the valve 192. Further, the exhaust mechanism notshown exhausts an atmosphere near the drivers of the transfer mechanism10. It should be noted that the nitrogen gas is continuously suppliedinto the heat treatment space 65 during the heat treatment of asemiconductor wafer W in the heat treatment apparatus 1. The amount ofnitrogen gas supplied into the heat treatment space 65 is changed asappropriate in accordance with process steps.

Subsequently, the gate valve 185 is opened to open the transport opening66. A transport robot outside the heat treatment apparatus 1 transportsa semiconductor wafer W subjected to the ion implantation through thetransport opening 66 into the heat treatment space 65 of the chamber 6.At this time, there is a danger that an atmosphere outside the heattreatment apparatus 1 is carried into the heat treatment space 65 as thesemiconductor wafer W is transported into the heat treatment space 65.However, nitrogen gas is continuously supplied into the chamber 6. Thus,the nitrogen gas flows outwardly through the transport opening 66 tominimize the outside atmosphere carried into the heat treatment space65.

The semiconductor wafer W transported into the heat treatment space 65by the transport robot is moved forward to a position lying immediatelyover the holder 7 and is stopped thereat. Then, the pair of transferarms 11 of the transfer mechanism 10 is moved horizontally from theretracted position to the transfer operation position and is then movedupwardly, whereby the lift pins 12 pass through the through holes 79 andprotrude from the upper surface of the holding plate 75 of the susceptor74 to receive the semiconductor wafer W. At this time, the lift pins 12move upwardly to above the upper ends of the substrate support pins 77.

After the semiconductor wafer W is placed on the lift pins 12, thetransport robot moves out of the heat treatment space 65, and the gatevalve 185 closes the transport opening 66. Then, the pair of transferarms 11 moves downwardly to transfer the semiconductor wafer W from thetransfer mechanism 10 to the susceptor 74 of the holder 7, so that thesemiconductor wafer W is held in a horizontal attitude from below. Thesemiconductor wafer W is supported by the substrate support pins 77provided upright on the holding plate 75, and is held by the susceptor74. The semiconductor wafer W is held by the holder 7 in such anattitude that the front surface thereof patterned and implanted withimpurities is the upper surface. A predetermined distance is definedbetween the back surface (a main surface opposite from the frontsurface) of the semiconductor wafer W supported by the substrate supportpins 77 and the holding surface 75 a of the holding plate 75. The pairof transfer arms 11 moved downwardly below the susceptor 74 is movedback to the retracted position, i.e. to the inside of the recessedportion 62, by the horizontal movement mechanism 13.

After the semiconductor wafer W is held in a horizontal attitude frombelow by the susceptor 74 of the holder 7 made of quartz, the 40 halogenlamps HL in the halogen heating part 4 turn on simultaneously to startpreheating (or assist-heating). Halogen light emitted from the halogenlamps HL is transmitted through the lower chamber window 64 and thesusceptor 74 both made of quartz, and impinges upon the lower surface ofthe semiconductor wafer W. By receiving halogen light irradiation fromthe halogen lamps HL, the semiconductor wafer W is preheated, so thatthe temperature of the semiconductor wafer W increases. It should benoted that the transfer arms 11 of the transfer mechanism 10, which areretracted to the inside of the recessed portion 62, do not become anobstacle to the heating using the halogen lamps HL.

The temperature of the semiconductor wafer W is measured with theradiation thermometer 20 when the halogen lamps HL perform thepreheating. Specifically, the radiation thermometer 20 receives infraredradiation emitted from the lower surface of the semiconductor wafer Wheld by the susceptor 74 through the opening 78 and passing through thetransparent window 21 to measure the temperature of the semiconductorwafer W which is on the increase. The measured temperature of thesemiconductor wafer W is transmitted to the controller 3. The controller3 controls the output from the halogen lamps HL while monitoring whetherthe temperature of the semiconductor wafer W which is on the increase bythe irradiation with light from the halogen lamps HL reaches apredetermined preheating temperature T1 or not. In other words, thecontroller 3 effects feedback control of the output from the halogenlamps HL so that the temperature of the semiconductor wafer W is equalto the preheating temperature T1, based on the value measured with theradiation thermometer 20. The preheating temperature T1 shall be on theorder of 200° to 800° C., preferably on the order of 350° to 600° C.,(in the present preferred embodiment, 600° C.) at which there is noapprehension that the impurities implanted in the semiconductor wafer Ware diffused by heat.

After the temperature of the semiconductor wafer W reaches thepreheating temperature T1, the controller 3 maintains the temperature ofthe semiconductor wafer W at the preheating temperature T1 for a shorttime. Specifically, at the point in time when the temperature of thesemiconductor wafer W measured with the radiation thermometer 20 reachesthe preheating temperature T1, the controller 3 adjusts the output fromthe halogen lamps HL to maintain the temperature of the semiconductorwafer W at approximately the preheating temperature T1.

By performing such preheating using the halogen lamps HL, thetemperature of the entire semiconductor wafer W is uniformly increasedto the preheating temperature T1. In the stage of preheating using thehalogen lamps HL, the semiconductor wafer W shows a tendency to be lowerin temperature in the peripheral portion thereof where heat dissipationis liable to occur than in the central portion thereof. However, thehalogen lamps HL in the halogen heating part 4 are disposed at a higherdensity in the region opposed to the peripheral portion of thesemiconductor wafer W than in the region opposed to the central portionthereof. This causes a greater amount of light to impinge upon theperipheral portion of the semiconductor wafer W where heat dissipationis liable to occur, thereby providing a uniform in-plane temperaturedistribution of the semiconductor wafer W in the stage of preheating.

To increase the directivity of light exiting the halogen lamps HL, thereflector 47 is provided on the outer wall surface of the glass tube 48of each of the halogen lamps HL. Supposing that the reflector 47 isprovided along the entire length of the glass tube 48 to cover the areaextending for 270 degrees from the lateral sides of the glass tube 48 tothe lower side thereof as shown in FIG. 9, a problem to be describedbelow comes up. FIG. 10 is a view showing a phenomenon occurring in alocation where the halogen lamps HL in the upper and lower tiers overlapeach other when the reflector 47 is provided over a wide area.

If the reflector 47 is provided to cover the area extending for 270degrees of the outer wall surface from the left-hand side of the glasstube 48 through the lower side thereof to the right-hand side thereof,only the area extending for 90 degrees of the outer wall surface on theupper side of the glass tube 48 is open. Thus, light emitted from thefilament 49 of a halogen lamp HL in the lower tier exits only the openupper portion of the glass tube 48.

However, if the reflector 47 is provided to cover the area extending for270 degrees from the lateral sides of the glass tube 48 to the lowerside thereof, the reflector 47 of a halogen lamp HL in the upper tier ispresent immediately over the halogen lamp HL in the lower tier in thelocation where the halogen lamps HL in the upper and lower tiers overlapeach other. Thus, light emitted upwardly from the halogen lamp HL in thelower tier is reflected downwardly by the reflector 47 of the halogenlamp HL in the upper tier to enter the glass tube 48 of the halogen lampHL in the lower tier again. As a result, the light emitted from thehalogen lamp HL in the lower tier is prevented from traveling toward thechamber 6, and repeats multiple reflection in the glass tube 48 in thelower tier, so that a support ring (not shown) holding down the filament49 is abnormally heated. The excessive heating of the support ringcauses the breakage of the glass tube 48 due to melting. As a result,the atmosphere flows into the glass tube 48 to also cause the breakageof the filament 49.

To overcome such a problem in the present preferred embodiment, thereflector 47 is provided such that the outer wall surface of the glasstube 48 of a halogen lamp HL in each of the upper and lower tiers isopen on the upper and lower sides, as shown in FIG. 8, in the locationwhere the halogen lamps HL in the upper and lower tiers overlap eachother. FIG. 11 is a view showing a phenomenon occurring in a locationwhere the halogen lamps HL in the upper and lower tiers overlap eachother when the reflector 47 is provided such that the upper and lowerportions thereof are open. It should be noted that FIG. 10 shows asection of the halogen lamp HL in the upper tier, whereas FIG. 11 showsa side surface of the halogen lamp HL in the upper tier.

When the reflector 47 is provided to cover the area extending for 90degrees of the outer wall surface on each of the opposite lateral sidesof the glass tube 48, the area extending for 90 degrees of the outerwall surface on each of the upper and lower sides of the glass tube 48is open (FIG. 8). When the area extending for 90 degrees of the outerwall surface on each of the upper and lower sides of the glass tube 48is open, light emitted from the filament 49 of the halogen lamp HL inthe lower tier exits the open upper and lower portions of the glass tube48.

In the location where the halogen lamps HL in the upper and lower tiersoverlap each other, the area extending for 90 degrees of the outer wallsurface on each of the upper and lower sides of the glass tube 48 isopen also in the halogen lamp HL in the upper tier. Thus, light emittedupwardly from the halogen lamp HL in the lower tier is transmittedthrough the open upper and lower portions of the outer wall surface ofthe glass tube 48 of the halogen lamp HL in the upper tier to enter thechamber 6 through the lower chamber window 64. As a result, the problemthat the light emitted from the halogen lamp HL in the lower tiertravels back to the glass tube 48 in the lower tier and repeats multiplereflection therein is avoided. This prevents the breakage of the glasstube 48 resulting from the abnormal heating of the support ring.

In the location where the halogen lamps HL in the upper and lower tiersdo not overlap each other, on the other hand, the reflector 47 isprovided to cover the area extending for 270 degrees of the outer wallsurface from the left-hand side of the glass tube 48 through the lowerside thereof to the right-hand side thereof, as shown in FIG. 11. In thelocation where the halogen lamps HL in the upper and lower tiers do notoverlap each other, light emitted upwardly from the halogen lamp HL inthe lower tier directly enters the chamber 6 through the lower chamberwindow 64, so that the aforementioned problem does not arise. Theprovision of such reflectors 47 increases the directivity of lightexiting the respective halogen lamps HL to provide a more uniformin-plane temperature distribution of the semiconductor wafer W in thestage of preheating.

The flash lamps FL in the flash heating part 5 irradiate the frontsurface of the semiconductor wafer W held by the susceptor 74 with aflash of light at the time when a predetermined time period has elapsedsince the temperature of the semiconductor wafer W reached thepreheating temperature T1. At this time, part of the flash of lightemitted from the flash lamps FL travels directly toward the interior ofthe chamber 6. The remainder of the flash of light is reflected oncefrom the reflector 52, and then travels toward the interior of thechamber 6. The irradiation of the semiconductor wafer W with suchflashes of light achieves the flash heating of the semiconductor waferW.

The flash heating, which is achieved by the emission of a flash of lightfrom the flash lamps FL, is capable of increasing the temperature of thefront surface of the semiconductor wafer W in a short time.Specifically, the flash of light emitted from the flash lamps FL is anintense flash of light emitted for an extremely short period of timeranging from about 0.1 to about 100 milliseconds as a result of theconversion of the electrostatic energy previously stored in thecapacitor into such an ultrashort light pulse. The temperature of thefront surface of the semiconductor wafer W subjected to the flashheating by the flash irradiation from the flash lamps FL momentarilyincreases to a treatment temperature T2 of 1000° C. or higher. After theimpurities implanted in the semiconductor wafer W are activated, thetemperature of the front surface of the semiconductor wafer W decreasesrapidly. Because of the capability of increasing and decreasing thetemperature of the front surface of the semiconductor wafer W in anextremely short time, the heat treatment apparatus 1 achieves theactivation of the impurities implanted in the semiconductor wafer Wwhile suppressing the diffusion of the impurities due to heat. It shouldbe noted that the time required for the activation of the impurities isextremely short as compared with the time required for the thermaldiffusion of the impurities. Thus, the activation is completed in ashort time ranging from about 0.1 to about 100 milliseconds during whichno diffusion occurs.

After a predetermined time period has elapsed since the completion ofthe flash heating treatment, the halogen lamps HL turn off. This causesthe temperature of the semiconductor wafer W to decrease rapidly fromthe preheating temperature T1. The radiation thermometer 20 measures thetemperature of the semiconductor wafer W which is on the decrease. Theresult of measurement is transmitted to the controller 3. The controller3 monitors whether the temperature of the semiconductor wafer W isdecreased to a predetermined temperature or not, based on the result ofmeasurement with the radiation thermometer 20. After the temperature ofthe semiconductor wafer W is decreased to the predetermined temperatureor below, the pair of transfer arms 11 of the transfer mechanism 10 ismoved horizontally again from the retracted position to the transferoperation position and is then moved upwardly, so that the lift pins 12protrude from the upper surface of the susceptor 74 to receive theheat-treated semiconductor wafer W from the susceptor 74. Subsequently,the transport opening 66 which has been closed is opened by the gatevalve 185, and the transport robot outside the heat treatment apparatus1 transports the semiconductor wafer W placed on the lift pins 12 to theoutside. Thus, the heat treatment apparatus 1 completes the heatingtreatment of the semiconductor wafer W.

In the present preferred embodiment, the reflector 47 is provided suchthat the outer wall surface of the glass tube 48 of a halogen lamp HL ineach of the upper and lower tiers is open on the upper and lower sidesin the location where the halogen lamps HL in the upper and lower tiersoverlap each other. Thus, light emitted upwardly from the halogen lampHL in the lower tier is transmitted through the open upper and lowerportions of the outer wall surface of the glass tube 48 of the halogenlamp HL in the upper tier, and is directed further upwardly. Thus, thelight is prevented from entering the glass tube 48 of the halogen lampHL in the lower tier again. As a result, this prevents the breakage ofthe glass tube 48 resulting from the abnormal heating of the supportring.

While the preferred embodiment according to the present invention hasbeen described hereinabove, various modifications of the presentinvention in addition to those described above may be made withoutdeparting from the scope and spirit of the invention. For example, inthe locations where the halogen lamps HL in the upper and lower tiers donot overlap each other, the reflector 47 may also be provided such thatthe outer wall surface of the glass tube 48 of each halogen lamp HL isopen on the upper and lower sides. When light emitted from the filament49 has a high energy density, the provision of the reflector 47 coveringthe area extending for 270 degrees of the outer wall surface from theleft-hand side of the glass tube 48 through the lower side thereof tothe right-hand side thereof as shown in FIG. 9 might cause the breakageof the glass tube 48 resulting from the abnormal heating of the supportring even in the absence of any halogen lamp HL thereover. In such acase, the reflector 47 is provided such that the outer wall surface ofthe glass tube 48 of each halogen lamp HL is open on the upper and lowersides in the locations where the halogen lamps HL in the upper and lowertiers do not overlap each other, whereby light emitted from the filament49 exits the open upper and lower portions of the glass tube 48. Thisprevents the breakage of the glass tube 48.

In the aforementioned preferred embodiment, the reflector 47 is providedsuch that the area extending for 90 degrees of the outer wall surface oneach of the upper and lower sides of the glass tube 48 is open. However,the angle of the open area is not limited to 90 degrees. As the angle ofthe open area of the outer wall surface on each of the upper and lowersides of the glass tube 48 decreases, the directivity of exiting lightincreases, whereas the risk of breakage of the glass tube 48 increasesdue to the decreasing light exiting area. Conversely, as the angle ofthe open area of the outer wall surface on each of the upper and lowersides of the glass tube 48 increases, the risk of breakage of the glasstube 48 decreases, whereas the directivity of exiting light decreases.

Although the 30 flash lamps FL are provided in the flash heating part 5in the aforementioned preferred embodiment, the present invention is notlimited to this. Any number of flash lamps FL may be provided. The flashlamps FL are not limited to the xenon flash lamps, but may be kryptonflash lamps.

Also, the number of halogen lamps HL provided in the halogen heatingpart 4 is not limited to 40. Any number of halogen lamps HL may beprovided. Further, the arrangement of the halogen lamps HL is notlimited to that in two tiers, i.e. upper and lower tiers, but thehalogen lamps HL may be arranged in one tier in a plane. When thehalogen lamps HL are arranged in one tier, there are no locations wherethe halogen lamps HL in the upper and lower tiers overlap each other,but the reflector 47 may be provided such that the outer wall surface ofthe glass tube 48 of each halogen lamp HL is open on the upper and lowersides for the purpose of preventing the breakage of the glass tube 48resulting from the emission of light having a high energy density fromthe filament 49 as mentioned above.

A reflector may be provided for each of the flash lamps FL of the flashheating part 5 in such a manner that the outer wall surface of the glasstube of each flash lamp FL is open on the upper and lower sides, as inthe aforementioned preferred embodiment. The provision of the reflectorsimilar to that of the aforementioned preferred embodiment on the glasstube of each of the flash lamps FL prevents the breakage of the glasstube while increasing the directivity of flashes of light.

Moreover, a substrate to be treated by the heat treatment apparatusaccording to the present invention is not limited to a semiconductorwafer, but may be a glass substrate for use in a flat panel display fora liquid crystal display apparatus and the like, and a substrate for asolar cell. Also, the technique according to the present invention maybe applied to the heat treatment of high dielectric constant gateinsulator films (high-k films), to the joining of metal and silicon, andto the crystallization of polysilicon.

Also, the technique according to the present invention is not limited tothe flash lamp annealer, but may be applied to single-wafer type lampannealers employing halogen lamps and CVD apparatuses. In such lampannealers, halogen lamps similar to those of the aforementionedpreferred embodiment may be provided over a chamber. When the halogenlamps are provided over the chamber, the reflector 47 is provided suchthat the outer wall surface of the glass tube 48 of each halogen lamp HLis open only on the lower side in the locations where the halogen lampsHL in the upper and lower tiers do not overlap each other.

Depending on the arrangement of the halogen lamps HL, the reflector 47is not necessarily required to be provided such that the outer wallsurface of the glass tube 48 of each halogen lamp HL is open on theupper and lower sides, but the reflector 47 may be provided such thatthe outer wall surface of the glass tube 48 of each halogen lamp HL isopen on one side of the glass tube 48 as seen in a radial directionthereof and on the other side thereof opposite the one side.

In the aforementioned preferred embodiment, the filament-type halogenlamps HL are used as continuous lighting lamps that emit lightcontinuously for not less than one second to preheat the semiconductorwafer W. The present invention, however, is not limited to this. Inplace of the halogen lamps HL, discharge type arc lamps (e.g., xenon arclamps) may be used as continuous lighting lamps to preheat thesemiconductor wafer W. In this case, the reflector 47 similar to that ofthe aforementioned preferred embodiment may be provided on each of thedischarge type arc lamps.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

What is claimed is:
 1. A heat treatment apparatus for heating asubstrate by irradiating the substrate with light, comprising: a chamberfor receiving a substrate therein; a holder for holding said substratein said chamber; and a plurality of rod-shaped lamps provided over orunder said chamber and for irradiating said substrate held by saidholder with light, wherein said rod-shaped lamps is arranged in two,upper and lower, tiers in a lattice pattern, wherein each of saidrod-shaped lamps includes: a cylindrical glass tube; and a reflectorprovided on an outer wall surface of said glass tube, wherein, as seenfrom a center of said glass tube, said reflector is provided to cover(1) said outer wall surface except upper and lower sides of said glasstube in a first location where said rod-shaped lamps in the upper andlower tiers overlap each other, and (2) said outer wall surface exceptthe upper side when the plurality of rod shaped lamps is provided undersaid chamber, or said outer wall surface except the lower side when theplurality of rod-shaped lamps is provided over said chamber, of saidglass tube in a second location where said rod-shaped lamps in the upperand lower tiers do not overlap each other.
 2. The heat treatmentapparatus according to claim 1, wherein said rod-shaped lamps arecontinuous lighting lamps.
 3. A heat treatment apparatus for heating asubstrate by irradiating the substrate with light, comprising: a chamberfor receiving a substrate therein; a holder for holding said substratein said chamber; and a plurality of rod-shaped lamps provided over orunder said chamber and for irradiating said substrate held by saidholder with light, wherein said rod-shaped lamps is arranged in two,upper and lower, tiers in a lattice pattern, wherein each of saidrod-shaped lamps includes: a cylindrical glass tube; and a reflectorprovided on an outer wall surface of said glass tube, wherein, as seenfrom a center of said glass tube, said reflector is provided to cover(1) said outer wall surface except upper and lower sides of said glasstube in a first location where said rod-shaped lamps in the upper andlower tiers overlap each other, and (2) said outer wall surface from alateral side to another lateral side of said glass tube through theupper side when the plurality of rod shaped lamps is provided under saidchamber, or said outer wall surface from a lateral side to anotherlateral side of said glass tube through the lower side when theplurality of rod-shaped lamps is provided over said chamber, in a secondlocation where said rod-shaped lamps in the upper and lower tiers do notoverlap each other.
 4. The heat treatment apparatus according to claim1, wherein the reflector is provided to cover an area extending for 90degrees of said outer wall surface on each of lateral sides of saidglass tube as seen from the center of said glass tube in the firstlocation where said rod-shaped lamps in the upper and lower tiersoverlap each other.
 5. The heat treatment apparatus according to claim3, wherein the reflector is provided to cover an area extending 90degrees of said outer wall surface on each of the lateral sides of saidglass tube as seen from the center of said glass tube in the firstlocation where said rod-shaped lamps in the upper and lower tiersoverlap each other.